Cause for Corrosive Action

The group has been working together to try and improve our performance on the project. For unresolved challenges our group is communicating with each other to overcome these challenges to the best of our ability. A new challenge we found is that we are not finding enough time to meet together. We usually end up getting together last minute to finish up our projects. Our group has decided to add more meeting days each week. At first we decided to meet every Wednesday and Sundays if needed. But now we have decided to meet every Monday as well as Wednesday during the week. This will give us more time to get our project done and not throw everything together last minute.

Component Summary

Part Name

Image

Function

Material Used

Manufacturing Process Used

Times Used

Foam Disc

Ammunition for gun.

Foam and plastic

Injection Molding

40

Gun Frame

To hold the gun and its components together

Polymer Plastic

Injection Molding

2

Cocking Handle

To be activated by a user in order to set the chamber.

Polymer Plastic

Injection Molding

2

Trigger

To set up a linkage in the gun to activate the chamber.

Injection Molding

Plastic

5

Gun Chamber

To produce energy within the gun in order to fire the foam disc outside of the chamber.

Polymer Plastic

Injection Molding

1

Drum Case

To hold the drum together with the stem so that it functions as it is intended to.

Polymer Plastic

Injection Molding

2

Drum Stem

To deliver discs from the drum to the gun.

Polymer Plastic

Injection Molding

1

Drum Shield

To protect the components within the drum to become hindered due to the interaction of foreign objects.

Plastic

Injection Molding

1

Spring (from barrel)

To push foam disc bullets through the drum stem to provide the gun with ammunition.

Pulling and Coiling

Steel

4

Spring (from reloading mechanism)

To have the ratchet mechanism on the drum to set itself each time that it is used.

Pulling and Coiling

Steel

1

Screw (frame)

To hold the two frame parts together

Forging and Threading

Steel

16

Drum Trigger

To rotate the barrel of the drum between four chambers.

Injection Molding

Plastic

1

Spring (from drum)

To put parts in the drum into place.

Pulling and Coiling

Steel

1

Plastic Cap (drum)

To set the drum trigger in place.

Injection Molding

Plastic

2

Spring Barrel Cap

To smoothly push discs through a barrel when the spring in the reloading mechanism is in place

Injection Molding

Plastic

4

Rod

To allow the drum trigger to smoothly rotate around an axis.

Forging

Steel

1

Drum Coil

To rotate the drum barrel each time that the drum trigger is activated.

Pulling and Coiling

Steel

1

Spring (drum trigger)

To set the drum trigger in place after each time that it is activated.

Pulling and Coiling

Steel

1

Drum Lid (top and bottom)

To set everything that is inside the drum in place.

Injection Molding

Plastic

2

Small Plastic Rod (drum)

To set the top and bottom of the drum lid in place.

Injection Molding

Plastic

4

Drum Barrels

To hold 40 disc bullets

Injection Molding

Plastic

1

Product Analysi=

Component Complexity Scale

1 - Is bland and performs almost performs no function

2 - Performs an inimportant function

3 - Performs a normal function(s)

4 - Performs an important function

5 - Performs multiple important functions

Interaction Complexity Scale

1 - Interacts with one component

2 - Only interacts with a few components

3 - Interacts with components and mechanisms

4 - In involved with multiple components/mechanisms

5 - In involved with multiple components/mechanisms at multiple amplitudes

Drum (Magazine)

Image 1: Drum (Magazine)

Component Function:

To rotate between four barrels, each filled with ten foam discs, to provide the gun with adequate ammunition. Beside providing the gun with ammunition, the drum also switches between four ammunition barrels for ease of adding ammunition to the drum. The mass flow associated with the drum are the discs that travel through the drum.

Component Form:

The drum is a three dimensional cylinder and the cylinder rotates about an axis. The drum weighs roughly 0.8 lbs. The drum has an approximate diameter of 134.19 mm and a height of 151.54 mm. The drum is made of a common plastic. The part was made by injection molding because of the small details and the mass production of the part for sale. A global factor of the material is that the plastic makes it look like a toy. A societal factor is that the drum is made so that parts, and the bullets, will not harm the users. An economic factor is that plastic is reasonably cheap material. The aesthetic purpose of the drum is too look like a toy, while at the same time, resembling a gun. That is why it is orange plastic, but shaped to look like a gun part.

Manufacturing Methods:

The part seems to be made by injection molding due to it being made of plastic. Also, injection molding is very common among toy parts. The part was made from plastic because it was cheap and shape was no obstacle for the manufacturing due to it being manufactured by injection molding. A global factor of manufacturing is that plastic is a rather universal material for production. A societal factor is that injection molding is a common use of manufacturing toys. An economic factor is that injection molding is less costly when making toys in the long run.

Component Complexity:

The drum is a reasonably complex component, being that it is a ratchet system that is used by a trigger and is held to a point by a spring. It rates 3 out of 5 on our scale as a component. Even though it is made from injection molding, the way all of the little piece interact together provide an interesting interaction. With multiple springs in the barrels and a trigger to control it, the drum rates 2 out of 5 on the interaction scale

Drum Stem

Image 2: Drum Stem

Function:

To transfer the foam disc ammunition from the drum magazine to the chamber inside of the gun. The stem provides for a mass flow of discs being transported from the barrel to the chamber.

Component Shape:

The stem is in no way symmetric, although, though it does come apart into two pieces when removed from the drum. The stem is 80.86 mm high and has a diameter of 45.33 mm. It weighs roughly 0.2 lbs. The tall, cylindrical shape of the stem is used so that the discs can be pushed through the stem by the spring without a problem. The stem is made from plastic, due to the common process of manufacturing these toy parts being injection molding.
The part was made by injection molding because of the small details and the mass production of the part for sale. A global factor of the material is that the plastic makes it look like a toy. A societal factor is that the drum is made so that parts, and the bullets, will not harm the users. An economic factor is that plastic is reasonably cheap material. The aesthetic purpose of the drum stem is too look like a toy, while at the same time, resembling a gun part. That is why it is orange plastic, but shaped to look like a gun part.

Manufacturing Methods:

The drum stem seems to be made by injection molding due to it being made of plastic. Also, injection molding is very common among toy parts. The part was made from plastic because it was cheap and shape was no obstacle for the manufacturing due to it being manufactured by injection molding. A global factor of manufacturing is that plastic is a rather universal material for production. A societal factor is that injection molding is a common use of manufacturing toys. An economic factor is that injection molding is less costly when making toys in the long run.

Component Complexity:

The drum stem is not a complex component and only rates a 1 out of 5 on our scale. It is simply a tube used to transport a disc from one place to another. Which also means that the interactions are simple, which also rates a 1 out of 5.

Chamber

Image 3: Chamber

Component Function:

The chamber gives the disc a channel to exit the gun. It also functions in aiding the guns design and gives a place for the cocking mechanism to attach to. It helps flow the energy through as the disc passes from the gun to outside.

Component Form:

The chamber is a long plastic piece that has a hollow center which is rectangular. It is three dimensional, 1ft x 2.7in x 1in. The shape is long and slender giving the disc a passage way to follow while leaving the gun. The chamber weighs approximately .8 pounds. The component is made from plastic. This is most likely because this gun is produced is mass quantities and injection molding is easy and fast to use. Any material could be used but plastic is cheaper and lighter to use. An economic factor that influenced this design is the price, it is cheap. A global factor is that it is on every gun so everyone knows what it looks like. An environmental factor is that the chamber doesn’t use energy. A societal factor is that the gun is safer with the chamber because it will not allow the gun to shoot out in random directions. The aesthetic purpose is to make the chamber smooth so it doesn’t hurt kids. It is bright orange so it is more appealing. The finish is paint which is aesthetic so it looks fun.

Manufacturing methods:

Injection molding was used to make this part. It is plastic, has an odd shape and riser marks. Plastic works well with injection molding. The shape was odd so injection molding was the best decision. An economical factor the influenced this decision was that it is cheap. A global factor was because plastic can be found all over the world. A societal factor is that it is safe for the manufacturers to use this method.

Component Complexity:

This is not a very complex component. Rates as 2 out of 5. The component form impacts complexity the most because it is made to look fun and cool but all it really needs to be to function is a straight chamber. The interactions are not very complex. It just gives a pathway for the disc to shoot out of the gun. Rates as 1 out of 5.

Spring Loaded Barrel (Drum)

Image 4: Springs

Function:

To push discs up into the stem of the drum. The spring loaded barrel transports discs from inside of the drum to the stem, which allows for a mass flow of discs through the drum.

Component Form:

The spring is a typical three dimensional helix with a plastic cap on the top to provide for smooth movement of the discs. The spring with the cap is roughly 190 mm high with a diameter of 30 mm. The shape of the spring and cap is meant to fit into a barrel of the drum to propel discs through the stem of the drum. The spring is made from steel, while the cap is made from plastic. Other springs in the gun are made by the same process and the cap is made just as the other small parts in the gun are made. A global factor is that both steel and plastic are common materials. A societal factor is that plastic and steel are commonly used in toys. An economic factor is that both of these materials are cheap. The cap is orange to go along with the orange pattern given by the other orange small pieces.

Manufacturing Methods:

The spring is made by a process of pulling and coiling, while the plastic cap is made by injection molding. Evidence to support this is that most springs are made by a process of pulling and coiling and that most small plastic parts in toys are made by injection molding. Shape was no obstacle in either manufacturing process. A global factor is that both materials are commonly used. A societal factor is that both materials are relatively safe. An economic factor is that both materials are cheap.

Component Complexity:

The spring loaded barrel is not complex and rates as a 1 out of 5. The component is simple a spring to raise discs up from the drum into the stem. The interactions also rate a 1 out of 5 because the spring only interacts with the discs.

Trigger

Image 5: Trigger

Component Function:

The trigger preforms the function of releasing the spring that holds the disc before it shoots out of the gun. This is the only function it preforms. This is all just energy flow because it transfers the potential energy being held in the spring into kinetic energy when the disc shoots out. This component functions inside of the gun.

Component Form:

The shape is small and rectangular but odd shaped. It is similar on both sides. It is 3 dimensional because the user needs to be able to pull it. It’s about 25mm x 10mm x 25mm. The shape has a slight curve to it so the user’s finger will be able to rest on it and not slide off easily. This is very light, weighing less than half a pound. The trigger is made from plastic most likely because it is cheap and light-weight. The plastic is hard so it should last a very long time. The aesthetic properties are that it is a bright orange color and it is smooth. This is so it looks appealing to kids and it should not hurt them. The finish is paint which is an aesthetic purpose so it is eye catching.

Manufacturing Methods:

Injection molding was used to manufacture this part. It has parting lines showing that it used this method. Plastic was used because of the economical factor that it is cheap. The shape is kind of odd so injection molding was a good method to use. A societal factor for why this was used is that the plastic is safe for kids to play with.

Component Complexity:

This component is not very complex. About a 2 out of 5. The function of the trigger makes it a little more complex because it must be able to handle constant pushing. The interactions are a little bit more complex. About a 2 out of 5. This is because when the trigger is pushed, it must release a spring which then allows the disc to shoot out of the gun.

Drum Shield

Image 6: Drum Shield

Component Function:

The drum shield protects the drum from foreign objects so that the drum can rotate without any problems. There is no flow associated with the component.

Component Form:

The drum shield is oddly shaped so that it fits around the cylindrical drum. The shield has a diameter of 130 mm, an inner diameter of 120 mm, a thickness of 2 mm and a height of 120 mm. The drum shield weighs less than 0.1 lbs. The drum shield was made from plastic. A global factor of the material is that the plastic makes it look like a toy. A societal factor is that the drum shield is made so that parts, and the bullets, will not become ajar and potentially harm the user. An economic factor is that plastic is reasonably cheap material. The aesthetic purpose of the drum shield is too look like a toy, while at the same time, resembling an attractive gun part. That is why it is orange plastic, but shaped to look like a gun part.

Manufacturing Methods:

Injection molding was used to manufacture this part. It has parting lines showing that it used this method. Plastic was used because of the economical factor that it is cheap. The shape is kind of odd so injection molding was a good method to use. A societal factor for why this was used is that the plastic is safe for kids to play with.

Component Complexity:

Since the only function of the part is to keep the drum free of unwanted interactions, the component is not complex at all and is a 1 out of 5. The drum shield only interacts with the drum and rates a 1 out of 5.

Cocking Handle

Image 7: Cocking Handle

Component Function:

The cocking handle provides a handle for the user to hold the gun, while at the same time, interacts with the chamber when the user activates the cocking handle by pulling it back. When pulled back, the cocking handle sets the chamber.

Component Form:

The handle is made of two sides of the handle in a tradition gun handle shape. The handle is 30 mm wide, 125 mm high and 94 mm long. The part weighs less than 0.1 lbs. The part is made from plastic because most of the parts of the gun are made from plastic. A global factor of the material is that the plastic makes it look like a toy. An economic factor is that plastic is reasonably cheap material. The aesthetic purpose of the cocking handle is too look like a toy, while at the same time, resembling an attractive gun part. That is why it is black and orange plastic, but shaped to look like a gun part.

Manufacturing Methods:

Injection molding was used to manufacture this part. It has parting lines showing that it used this method. Plastic was used because of the economical factor that it is cheap. The shape is kind of odd so injection molding was a good method to use. A societal factor for why this was used is that the plastic is safe for kids to play with.

Component Complexity:

The part is now very complex and rates a 1 out of 5 because it simply acts as a handle unless the user activates the cocking mechanism. The cocking handle can both interact with the user and the chamber, so the interaction is rates as a 2 out of 5.

Solid Modeled Assembly

The components in the trigger interact together in almost a linkage mechanism to activate the chamber. We used Inventor Professional 2013 to show these components individually in a solid model assembly.

Trigger

Coil

Screw

First Trigger Link

Second Trigger Link

Trigger Assembly

Engineering Analysis

Cocking Mechanism

The cocking mechanism is an important function that sets a spring to allow the disc to be shot out of the gun. Using engineering analysis, the engineer can determine the best spring to be used. Also, they can determine how far back the cocking mechanism should set the spring before it is released to shoot the disc. To figure out the best spring to use, the engineer can lay out a chart. Using experimentation, the engineer can test out different springs with different spring constants (k). Also, they can figure out the greatest distance (x) to stretch the spring to fire the disc the proper distance. Another factor when choosing the perfect spring is to find a spring that will last through being stretched so many times. The spring must have a high fatigue rate.

Problem Statement:
The cocking mechanism sets the spring in a position so that when the trigger is used, the spring releases and shoots out the disc. How far should the spring be set for the disc to shoot at a reasonable speed and distance? It should be fast enough to leave the chamber but not so fast that it hurts if shot.

Diagram:

Assumptions:

The barrel is nearly frictionless so assume friction will have no effect on the disk

The cocking mechanism sets the spring at the same distance every time

The gun is shot in a horizontal position (parallel to the ground)

Governing Equations:

Fs = -kx (1)

PE = ½ kx^2 (2)

KE = ½ mv^2 (3)

Calculations:
The engineer would first buy many different springs. He would then test them on how far they stretch. He can use equation one to figure out spring constants for each spring. A computer program could help when analyzing this. Equations two and three can help determine the energy that the spring converts and transfers to the disc for when it shoots out. The greater the potential energy, the greater the kinetic energy that the disc receives, and the faster the disc will shoot out.

Solution Check:
After many different tests for different springs at different lengths, the engineer should re-check the spring they chose. They would test it over and over again to make sure it lasts a long time and shoots the disc at the desired speed. The faster the engineer can get the disc to shoot out, the farther the disc will fly giving children a toy that is more fun to play with.

Discussion:
The best spring to be used is one that is small (less than one inch) and is tough enough to withstand constant stretching and releasing. The spring will allow the disc to shoot out at a velocity of approximately 10.4 m/s. This speed is not fast enough to seriously injure a child but it is fast enough to allow the disc to fly a good distance. The discs can shoot about 35 feet if not affected by wind or other objects. The best spring will last for many years even though it constantly gets stretched.

Design Revision

Drum Trigger (Geneva Stop)

One revision that could be made is that the trigger on the drum could be replaced with a geneva stop mechanism. This would allow for a constant rotation of a part and less parts used so that the possibility of a failing part in the mechanism would greatly decrease. This would mean that the gun would operate more productively. Since there will just be different plastic parts in the gun, cost will not be greatly effected. A societal factor that results from this change is that the gun would now look like more of a child's toy and less of a dangerous gun, which would appeal to a younger audience of costumers.

No Trigger

Another revision that could be made would be to completely take the trigger out of the gun. Instead, the disc would be loaded and shot when the gun was cocked by the cocking handle. The disc would go in the chamber and immediately by projected out of the gun when the cocking handle is set back to its normal position. This would lead to another societal factor of the gun looking more like a child's toy, due to it being a pump gun, essentially. The gun might now also be much cheaper since much of the small parts are being completely disregarded.

CO2 Cocking Mechanism

Another revision would be to take out the cocking mechanism and replace it with a CO2 cartridge to set and load the chamber. The gun would end up working much like a paintball gun works. This would make the gun fire at a much faster rate and at a much faster velocity. As a societal factor, the gun would be much less safe and be projected to market to an older audience. As an economic factor, the gun might cost more, but that would be justified since you are marketing to older customers.